Aggregation-induced emission luminogen based self-healing hydrogels fluorescent sensors for α-amylase

The development of self-healing hydrogels with an adjustable fluorescence still remains a challenge, owing to the water-induced aggregation-caused quenching nature of traditional organic luminogens. In this work, a fluorescent self-healing hydrogel with a dual network was designed, in which the host-guest recognition of tetraphenylethylene (TPE) modified poly(l-glutamic acid) (PLGA-TPE) with acrylate gamma-cyclodextrin (Ac-gamma-CD) was strengthened by the second chemical crosslinking of Ac-gamma-CD with acrylamide. Taking advantage of the host-guest recognition, the fluorescence of the TPE moieties has been suppressed in the hydrogel, and then the dual-network architecture of the hydrogel can be degraded by alpha-amylase cutting the alpha-1,4 glycosidic bonds of Ac-gamma-CD, enabling the hydrogel to fluoresce. The fluorescence of the hydrogel increases gradually, and the mechanical properties decrease simultaneously, indicating a relationship between the degree of hydrolysis of Ac-gamma-CD and the disruption of the stable network architecture of the hydrogel. This dual-network hydrogel possesses a fast self-healing ability and the recovery ratio reached almost 100% in 3 min owing to the dynamic nature of the host-guest recognition. Furthermore, by altering the temperature of the system, the fluorescence intensity of the hydrogel can be changed reversibly. Thus, through host-guest recognition, both the network architecture and the fluorescence behavior of this fluorescent self-healing hydrogel could be modulated, and it can therefore potentially be used as an alpha-amylase sensor or an indicator of the viscoelastic behavior of the hydrogel.

Automated summary

In this work, a fluorescent self-healing hydrogel with a dual network structure was developed, where the fluorescence behavior was modulated through host-guest recognition, allowing for fast self-healing and high fluorescence intensity. This hydrogel shows potential for applications as an alpha-amylase sensor or indicator of viscoelastic behavior.